Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
h,w=map(int,input().split())
grid=[["#"]*(w+2)]+[list("#"+input()+"#") for x in range(h)]+[["#"]*(w+2)]
sx,sy=1,1
gx,gy=w,h
loc=[[sy,sx]]
ans=sum(i.count(".")for i in grid)
for c in range(h*w):
    next_loc=[]
    for y,x in loc:
        for i,j in([0,1],[1,0],[0,-1],[-1,0]):
            if grid[y+i][x+j]=='.':
                grid[y][x]=c+1
                grid[y+i][x+j]=c+2
                next_loc.append([y+i,x+j])
    loc=next_loc
    if [gy,gx] in loc:
        ans-=grid[gy][gx]
#        for i in grid:
#            print(*i)
        print(ans)
        exit()
print(-1)